20w4d with contractions

Jody

I’m 20 weeks and 4 days pregnant and while at work I got hit in the abdomen. I then started leaking a watery like substance and cramping. Went to the hospital and they hooked me up to a machine to tell if I was having contractions and how far apart they are, and they were 18 minutes apart. Has this happened to anyone else before and should I be worried? I’ve already had one miscarriage before so it makes me very nervous.